Sets focus to a field.

<div class="definition">
    setFocus([focus])
</div>

<div class="arguments">
    <table>
    <tr>
        <td>focus</td>
        <td><b>string|number</b>, id of the field or index of the filed</td>
    </tr>
    </table>
</div>

Returns JQuery object or <i>undefined</i>.

<h4>Description</h4>

This method will set the focus to a field determined by <span class="argument">focus</span>.
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If the <span class="argument">focus</span> argument is not set, form<a class="argument" href="w2form.focus">.focus</a> will be used.
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If a field to focus is found, the JQuery object of the field will be returned. If no field is found, <i>undefined</i> is returned.
